What are my chances on a car loan?

I'm 18. I've had a VISA credit card from my State Farm Insurance, I got without a co-signer, for 6 months and have been paying it not only every month, but every 2 weeks(I pay half of the balance every two weeks then have a 0 balance at the end of the month,then start using it again. I've never had to pay interest because I pay way more than the minimum balance). They raised my credit limit in the first 3 months from $500 to $1,000. I also pay a $72.91 phone bill and a $87.88 insurance bill. Total, my bills a month average to about $500 - $600. I get paid $1,300 a month after taxes. I live at home and don't have to pay rent or anything. What are my chances of getting a $20,000 car loan from my CREDIT UNION without a co-signer? If that doesn't work should I apply for a loan through State Farm(they already do my credit card and insurance)?